HELP ON A WORK PROBLEM CAN'T DO IT BY MYSELF SNIFF SNIFF.:cry:

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To calculate the work done in lifting a uniform ladder from a horizontal to a vertical position, the center of mass must be raised. The ladder has a mass of 12 kg and a length of 4.6 m, meaning the center of mass is at 2.3 m when horizontal. The work done equals the increase in gravitational potential energy, calculated using the formula mgh, where h is the height of the center of mass. Since there is no kinetic energy involved, the focus remains solely on the potential energy change. The discussion confirms that the approach to use mgh for the entire ladder is correct.
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a uniform ladder of mass 12kg is 4.6m long. if it is lifted from a horizontal to a vertical position, how much work is done

i just thought because i have to lift the centre of the mass, i'd have to do mgh with h being 2.3m. I think i am sure that i don't have the right answer. Sniff.. help please!
 
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I think you are correct.
 
HAHA... oh... thanks.
 
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The work must equal the potential energy increase for the ladder (since there isn't any kinetic energy relevant for this problem).

But the potential energy increase for the WHOLE ladder, is simply the ladder's mass multiplied with g and the C.M's position, since the gravitational potential energy is linear in the vertical position coordinate.
 

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